The refractive index of the material of the prism is √3, then the angle of minimum deviation of the prism is :

A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will

The angular resolution of a 10 cm diameter telescope at a walength of 5000 Å is of the order of

Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is is

If f_v and f_n are the focal lengths of a convex lens for violet ad red light respectively and F_V and F_R are the focal lengths of concave lens for violet and red light respectively, then we have

A transparent cube contains a small air bubble. Its apparent distance is 2 cm when seen through one face and 5 cm when seen through other face. If the refractive index of the material of the cube is 1.5, the real length of the edge of cube must be :

A telescope has an objective lens of 10cm diameter and is situated at a distance of one kilometre from two objects. Find out the minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Å.

The wavelength of light of frequency 100Hz is :

An astronomical telescope of ten fold angular magnification has a length of 44 cm. The focal length of the objective is

Colours of thin soap bubbles are due to